A Review of New Micro-Extraction Methods: A Comparison of Techniques and Applications

Solid phase microextraction and liquid phase microextraction methods have been considered due to the elimination of the use of toxic and harmful solvents for the environment and human health. For this reason, modification and enhancement of micro-extraction methods is also one of the important topics in research. Microextraction methods, in addition to removing toxic solvents, have increased efficiency, accuracy, and greatly reduced the time and cost of analysis. But these methods have two serious limitations. First, in solid samples such as soil and medicine, the analytes are firmly attached to the tissue and do not separate easily. it is difficult or impossible to catch highly volatile materials with these methods. The best approach to overcome these limitations is to cool the adsorbent and simultaneously heat the sample tissue, a technique that dramatically increases the extraction efficiency. Another method to increase the extraction efficiency is vacuum-enhanced micro-extraction technique. In this system, the pressure inside the vessel is drastically reduced and the extraction speed and efficiency are significantly increased compared to normal SPME, leading to an increase in sensitivity and a shorter sampling time. With this device, all types of solid and liquid samples can be easily extracted and analyzed directly without manipulation and change in the sample. In this research, we will have an overview of micro-extraction methods and their enhanced techniques and a general comparison between these techniques